LCLS Conceptual Design Report - Stanford Synchrotron Radiation ...

L C L S C O N C E P T U A L D E S I G N R E P O R T
4.6.1 Wakefield Theory................................................................................................. 4-19
4.6.2 Wakefield Effects on the LCLS ........................................................................... 4-20
4.7 Emittance and Charge Control......................................................................................... 4-22
4.8 Control of X-Ray Pulse Length and Linewidth............................................................... 4-23
4.8.1 Pulse Length Control............................................................................................ 4-23
4.8.2 Linewidth Control ................................................................................................ 4-24
4.9 References ....................................................................................................................... 4-25
5 FEL Parameters and Performance
Technical Synopsis ....................................................................................................................... 5-1
5.1 Introduction ....................................................................................................................... 5-2
5.2 The Basic LCLS FEL Design ............................................................................................ 5-2
5.2.1 Overview................................................................................................................ 5-2
5.2.2 Slice Parameters ..................................................................................................... 5-3
5.2.3 Parameter Optimization.......................................................................................... 5-4
5.2.4 The Nominal Parameter Set ................................................................................... 5-5
5.2.5 Working Points ...................................................................................................... 5-6
5.3 Electron Beam Focusing Along the Undulator.................................................................. 5-7
5.3.1 Optimum Beam Size .............................................................................................. 5-7
5.3.2 Natural Undulator Focusing................................................................................... 5-9
5.3.3 Focusing Method (Lattice)................................................................................... 5-10
5.3.4 FODO Lattice Layout........................................................................................... 5-13
5.4 Computer Simulations ..................................................................................................... 5-13
5.4.1 FEL Simulations Codes........................................................................................ 5-13
5.4.2 Start-To-End Simulations..................................................................................... 5-14
5.4.2.1 Case I - Low Charge Limit .................................................................. 5-14
5.4.2.2 Case II - High Charge Limit ................................................................ 5-17
5.5 Sources of Gain Reduction .............................................................................................. 5-18
5.5.1 Undulator Trajectory Errors................................................................................. 5-18
5.5.1.1 Undulator Steering and Corrector Description .................................... 5-18
5.5.1.2 Magnetic Field Errors .......................................................................... 5-18
5.5.1.3 Undulator Trajectory Straightness Tolerances..................................... 5-19
5.5.1.4 Steering Stations Separations............................................................... 5-19
5.5.1.5 Undulator Trajectory Matching Tolerances......................................... 5-19
5.5.2 Effects of the Emission of Spontaneous Radiation on Gain................................. 5-20
5.5.2.1 Average Energy Loss........................................................................... 5-20
5.5.2.2 Energy Spread Increase ....................................................................... 5-21
5.5.2.3 Emittance Increase............................................................................... 5-21
5.6 Electron Beam Tolerances............................................................................................... 5-21
5.6.1 Electron Beam Tolerance Goals........................................................................... 5-21
5.6.2 Pulse-To-Pulse Intensity ...................................................................................... 5-23
5.6.2.1 Jitter at Saturation ................................................................................ 5-23
5.6.2.2 Jitter in the Exponential Gain Regime ................................................. 5-25
T A B L E O F C O N T E N T S